Some 1 million workers across the city will soon able to call in sick without losing a day’s salary, under a deal struck yesterday to make small businesses provide paid days off for illness.

The measure comes after City Council Speaker Christine Quinn dropped her long-standing opposition to a paid-sick-days bill.

The new legislation — which Quinn is expected to tout at City Hall today — will give workers at small companies their salary for up to five sick days a year.

Quinn has been facing growing criticism from other mayoral candidates for blocking paid sick leave — as well as a threatened move by council members to take up the bill without her support, sources said.

Under the compromise proposal hammered out by Quinn, a sick-leave mandate would initially apply to companies with 20 or more employees, requiring them to provide five sick days annually.

An earlier bill that Quinn had blocked would have forced companies with as few as five workers to provide paid sick time.

Quinn negotiated a new bill among members of the council, union leaders and city business leaders. The last group had long opposed the costly mandate.

“Throughout these negotiations, I have always said that I was willing to listen and engage all sides,” Quinn said last night, insisting the bill “balances the interests” of workers and business owners.

But in backing paid sick leave, Quinn is setting up another conflict with her political ally Mayor Bloomberg, who has adamantly opposed the measure as a burden on small businesses.

Bloomberg did not have a comment on yesterday’s deal, but on Wednesday, he criticized the prospect of such legislation.

“I personally think it’s best left to the employer, and you can take a job or not take a job depending on the salary and benefits that the employer offers,” he said. “There are small companies that couldn’t possibly survive.”

Quinn says she has the votes to override a Bloomberg veto.

If the sick-leave mandate becomes law, it would kick in on April 1, 2014 — a later start that’s a concession to the business community, giving firms time to prepare and in hopes the economy will improve.

Quinn plans to say today that if the economy tanks between now and the new start date, the legislation would not go into effect, sources said.

When asked why she opposed mandating paid sick days as recently as last week, a source close to Quinn replied, “Chris has always said she wants to protect small businesses.

“This bill protects small businesses by making it 20 [employees], and above and at the same time ensures that it only goes into effect in an up economy, not a down economy.”

The legislation would become more stringent by October 2015, when it would apply to firms with 15 or more workers, sources said.

The deal, first reported by The Post, has the support of a key labor union whose endorsement Quinn is seeking in her run for mayor — Local 32BJ of the Service Employees International Union.

It got a tepid sign-off from Kathy Wylde, president of the city’s leading business group, the Partnership for New York City.

“To the extent that the council is going to pass something, obviously, we want them to pass the bill that’s least damaging to business and the economy,” she said.

“Assuming they agree to a bill that is significantly less damaging than what’s currently on the table, we’d support that effort.”